Balloon-type catheters are well known. Basically, these devices have an elongated wire-like catheter provided with a distal end adapted to be inserted into a patient's blood vessel, and provided with a proximal end adapted to remain outside the patient's body. An inflatable balloon is typically mounted on the distal marginal end portion of the catheter. Hence, the surgeon will make an incision in a blood vessel; insert the catheter, with its balloon deflated, through the incision into the blood vessel; and feed the catheter along the blood vessel to a desired position relative thereto. This position may be determined by conventional fluoroscopic techniques.
Once in position, the balloon may be selectively inflated, and the catheter may, if desired, be moved longitudinally relative to the blood vessel to perform some desired procedure. In some cases, however, the balloon is simply inflated, without any longitudinal movement relative to the blood vessel, so as to deform plaque outwardly, thereby to increase the size of a constriction within the blood vessel. This procedure is commonly known as angioplasty.
In other situations, the catheter is moved relative to the blood vessel with the balloon inflated. For example, to remove an embolus, such as a blood clot, the conventional balloon catheter is commonly passed through the embolus with its balloon deflated. Thereafter, the balloon is selectively inflated, and the proximal end of the catheter is pulled from outside the body in an attempt to physically remove the embolus from the blood vessel.
However, with such prior art techniques, the catheter is commonly inflated to a pressure substantially above the patient's systolic blood pressure in order to sufficiently stiffen the balloon to an extent necessary to dislodge an embolus when moved longitudinally relative to the blood vessel. Thus, the inflated balloon typically bears forcibly against the blood vessel. This condition may weaken the wall of the blood vessel, and tend to promote an aneurysmic condition. At the same time, such conventional catheters commonly inflate the balloon to a toroidal shape, and do not have any cavity or recess for receiving portions, if not all, of the separated embolus. Even when inflated, the toroidal shape of prior art catheters has a tendency to roll or deform to a teardrop shape when the inflated balloon frictionally engages the wall of the blood vessel and/or the embolus.
Accordingly, there is believed to be a need for an improved balloon-type catheter for use in performing an embolectomy, which catheter may be inflated to a particular shape having a concave annular recess arranged to face toward, and receive portions of, the separated embolus. At the same time, there is believed to be a further need for a particular type of balloon catheter which need not necessarily be overinflated so as to bear forcibly against the walls of the blood vessel. It is further perceived that such an improved catheter would have the advantage of reducing damage to the endothelial layer of the blood vessel.